1. Field of the Invention
The present invention relates generally to computer systems with memory and, more particularly, the present invention relates to a computer system having insertable non-volatile memory modules.
2. Related Art
Computer systems always include at least one memory store. A typical computer system includes a main memory store and at least one type of non-volatile memory. The main memory store typically uses fast, volatile memory to store an operating system and programs that run while the computer is operating. The volatile memory typically comprises random access memory (RAM) and is considered the main memory for the computer system. The non-volatile memory is used to store data and programs without fear of loss upon power down, power interruptions, or computer malfunction. The non-volatile memory typically comprises a hard disk drive, floppy drive, or CD drive. The non-volatile memory is typically considered the secondary memory for the system.
The main memory, or RAM, is typically smaller in size, faster in speed, and more expensive in cost, than the secondary memory storage. Practically all current non-volatile memory storage technologies, such as magnetic hard drives, magnetic tape or floppy drives, optical media, magneto-optic, phase-change, polymer, plastic, FLASH, as well as other media, are slower by at least one order of magnitude than the RAM technologies currently available and are often several orders of magnitude slower. RAM technologies include static RAM (SRAM) and dynamic RAM (DRAM), both of which have their advantages and disadvantages and are used extensively in today's computer systems.
Computer systems have advanced to the stage where certain peripheral devices can be “hotplugged” directly into the computer system while it is operating. The computer system will recognize the peripheral device and accept it as if it had always existed from the time of bootup or powerup for the computer system. “Hotplugging” is defined as the ability to insert or remove a peripheral device within the computer system while it is running.
Volatile memory requires that it be powered constantly in order for the contents of the memory to be preserved. Thus, a volatile memory cannot utilize the hotplugging capability provided in today's computer systems without a loss of data either prior to insertion or after loss of power while inserted in the system. Furthermore, an abrupt power surge or drop can be catastrophic to such memory and is to be avoided. Otherwise, the memory will be destroyed or at least damaged to some extent.
Recent advances in memory technology have included the development of magnetic RAM (MRAM). MRAM stores information magnetically, so it does not require a constant power supply, as does current RAM technology. This quality is known as non-volatility. MRAM can offer all the advantages in speed and size that volatile memory offers and brings the added advantage of being non-volatile and, in some architectural configurations, cheaper to manufacture. MRAM can operate at speeds similar to either SRAM or DRAM, thus allowing it to be utilized within main memory.
It is desirable to provide a memory module system that can be inserted within a computer system during operation in such a way as to avoid losing the module's prior memory state and to avoid catastrophic failure of either the module or the computer system that would otherwise result in prior art memory systems.